Coating apparatus having opposed atomizing nozzles in a fluid bed column

Abstract

A fluid-bed particle coater (10) having a dual-jet and spray arrangement and including an upstanding column (15) which has an upper cylindrical section (15a), a tapered intermediate section (15b) and lower cylindrical section (15c). Depending from the lower cylindrical section (15c) is a cylindrical chamber (30) which is inner-connected to tubular sections (31,37) adapted for introducing multiple air streams via separately controlled inlet openings (32,36,38). The dual-jet and spray construction includes an upwardly-facing spray nozzle (40) positioned in coaxial relationship to the tubular sections (31,37) and a draft tube (50) and downwardly facing spray nozzle (25) contained within a fountain tube (20) which is disposed above the draft tube (50). The fountain and draft tubes (20,50) concentrically intersect about the intermediate section of the column in an opened telescopic arrangement. The dual-jet and spray particle coater provides multiple coating and drying zones and is conveniently adapted with a completely integrated computer control system (200) that provides for automatic and continuous monitoring and control of all fluid flow rates, temperatures and critical pressure measurements throughout the fluidized coating system. <IMAGE>

We claim: 
     
       1. An apparatus for spray coating discrete particles while such particles are suspended in a apparatus, said apparatus comprising, in combination: an upstanding column including an upper cylindrical body section provided with a vent, a downwardly tapered intermediate section and a lower cylindrical section, said tapered intermediate section and said lower cylindrical section housing a vertically extending draft tube;   a vertically positioned fountain tube adapted with an air inlet port and a spray extension terminating in opposing air and liquid inlets and extending axially above said upper cylindrical body section, said fountain tube housing a downwardly-facing atomizing spray nozzle and having a greater diameter than said draft tube, wherein both tubes concentrically intersect within the column in an opened telescopic dual-jet and spray arrangement;   a cylindrical inlet chamber depending from and communicating with said lower cylindrical section, said cylindrical inlet chamber being provided with an air entry port and containing a jet inlet tube and an upwardly-facing atomizing spray nozzle positioned in coaxial relationship to said jet inlet tube and said draft tube;   a tubular channel which depends from said cylindrical inlet chamber and communicates with said jet inlet tube, said tubular channel being provided with a swirl flow inlet line;   an air inlet tubular chamber which depends from and communicates with said tubular channel, said tubular chamber being adapted with an air inlet opening and having a centrally protruding spray extension provided with terminally opposing air and liquid inlets; and   regulating means for controlling flow distribution and flow rates within the apparatus and for controlling temperatures of all inlet streams to the apparatus.   
     
     
       2. The apparatus according to claim 1, wherein said jet inlet tube is arranged annularly around said upwardly-facing atomizing spray nozzle. 
     
     
       3. The apparatus according to claim 2, wherein said upwardly-facing atomizing spray nozzle is adjustably mounted to move up and down in said jet inlet tube and vertically extend into the lower portion of draft tube to optimize its location. 
     
     
       4. The apparatus according to claim 3, including a screen with an opening which extends across a jet tube outlet to prevent particles from falling into the jet tube when the upwardly-facing spray nozzle extends beyond said jet tube outlet. 
     
     
       5. The apparatus according to claim 1, wherein said air entry port of the cylindrical inlet chamber is arranged to provide aeration flow to an annular zone surrounding said draft tube. 
     
     
       6. The apparatus according to claim 1, wherein said lower cylindrical section contains a perforated cylindrical insert covered by a screen to prevent the particles from falling into the cylindrical inlet chamber before and after the coating operation, said insert and said screen having central openings which communicate with the top of said jet inlet tube. 
     
     
       7. The apparatus according to claim 6, wherein the distance between said top of the jet inlet tube and a bottom inlet to said draft tube is adjustable. 
     
     
       8. The apparatus according to claim 7, wherein said draft tube is adjustably mounted within said column to vary said distance between said top of the jet inlet tube and the inlet to said draft tube. 
     
     
       9. The apparatus according to claim 1, wherein said downwardly-facing atomizing spray nozzle is adjustably mounted to slide up and down within the fountain tube to optimize its location. 
     
     
       10. The apparatus according to claim 1, including a screen which extends across the bottom of said tubular channel to prevent particles from falling into the tubular chamber when the upwardly-facing spray nozzle is positioned within said jet inlet tube. 
     
     
       11. The apparatus according to claim 1, further comprising pressure regulator means, whereby air streams to both said spray extensions are separately controlled by said pressure regulator means which feed ambient air at volumetric flowrates into said downwardly-facing and upwardly-facing spray nozzles. 
     
     
       12. The apparatus according to claim 1, further comprising a peristaltic pump, whereby liquid streams to both said spray extensions are by controlled said peristaltic pump. 
     
     
       13. The apparatus according to claim 1, further comprising individual heaters to control the temperatures of the inlet air streams. 
     
     
       14. The apparatus according to claim 13, wherein each of said heaters are connected in series to mass flow controllers. 
     
     
       15. The apparatus according to claim 1, further comprising thermocouple probe and pressure probe means for monitoring temperatures and pressures within said column. 
     
     
       16. The apparatus according to claim 1, wherein said regulating means are in electronic communication with the a computerized data acquisition and control system. 
     
     
       17. The apparatus of claim 16, wherein said data acquisition and control system comprises a completely integrated computer control system provided with output means.